Pump piston



Jan. 20, 1931. w. F. Mc MAHON 1,789,318

' PUMP PISTON Filed June 7, 1929 A 7//l////////// /f//// A Patented Jan. 20, 1931 UNITED STATES WILLIAM FREDERICK-MOMAHON, F RIVERSIDE, CALIFORNIA I BUM? PISTON Application file d June 7, 1929. Serial No. 869,085.

This invention relates to pistons applied to pumps or other mechanisms and especially to reciprocating pumps.

An object of this improvement is to provide an assemblage of fixed, and moving parts adapted to utilize a fluid pressure to compress and/or expand a pliable packing in a piston.

A further object is to provide a mechanism adapted to hold the pliable packing, of a piston, in its compressed and/or expanded state or form after a fluidvpressure has so compressed or expanded the said pliable packin An o bject is to provide an assemblage of fixed and moving parts so arranged so as to utilize the fluid pressure in a pum to compress the pliable packing element 0 the said assemblagewhereby, the said pliable packing is Held in its form or state'by an element upon which the said fluid pressure has acted upon.

A further object is to-provide a simple eflicient construction to perform the above objects, which construction will be adapted to be fixed on a piston rod of the pump and contain but three elements exclusive of the pliable piston packing, two of the said elements being fixed against longitudinal move- .ment and the other longitudinally movable and adapted to be acted upon by the fluid pressure in the pump to be moved toward the said pliable piston packing bya rotating movement caused by the fluid pressure acting thereon. 1

Another object is toprovide an element, in a pump piston, that will be rotated by the fluid pressure in the said pump in which the said element is a part of the piston of the pump.-

W1th these and other objects in view, the invention resides and consists in the construction and novel combination and arrangement of parts hereinafter more fully described, illustrated in the accompanying drawings, and pointed out in the claims hereto appended, it being understood that various changesin the form, proportion, size and minor de tails of construction within the scope of the claims may be resorted to without departure from the spirit or sacrificing any of the advantages vof the invention.

Similar characters of reference denote like or corresponding parts throughout the sev eral figures of the accompanying drawings formin a part of this specification, and upon w ich,

Figure 1 is a central longitudinal section through my improved piston construction.

Figure 2 is an outside longitudinal view of my adapter 2 showing the lead of the threads.

Figure 3 is a transverse section through the piston, showing the general'formation of the various parts;

Referrin in detail to the characters of reference mar ed upon the drawings, 1 represent the piston rod of a reciprocating pump in which a. water liner 3 is incorporated. It is in this water liner 3 m piston unit 4 reciprocates, being moved y a force acting upon the piston rod 1. Piston rod 1 is,in this case, a typical piston rod in a reciprocating pump and may be moved by steam pressure or other means, however as my improvement resides in a pump fiston, I believe that further'description o the pump in which it is used would be superfluous, as a reciprocating pump is well known. So I will only describe my piston unit improvement. It may be well to note that while I mainly intend to apply my improved piston to reciprocating pumps, it may obviously be used in any type or form of mechanism and used to equally good advantage. It is my intention to construct my piston so that it may be used on a. piston rod of a commercial type pump in lieu of any other type of piston or in other words, to be used on the piston rod furnished by the respective pump manufacturer. In my improvement I use the fluid pressure in the pump to compress and/or expand the pliable piston packing) 5. The main object of my improvement eing that of a mechanism 6 adapted to'hold the pliable packing 5 in its compressed and/or expanded form or state after the fluid pressure in the pump has so compressed or expanded said pliable packing 5. The main object heretofore of fluid expanded pistons was that the fluid pressure acting upon the piston packing would cause a pulsative action thereto and aloss in me-- chanical eificiency to the pump in which they were used. By my improvement it sufiices to say that this plusative action will'be substantially eliminated and the mechanical efficiency of the pump benefited. Also my adjusting element 7 will be rotated by the fluid pressure acting thereon, this feature is absolutely new in the art and constitutes one of my most important features of construction. By referrin to Figure 1, of the drawing hereto appende it will be noted that by the extra large lead of the threads 8, wherein the thread angle is made larger than the friction angle,

that when the piston 4 is pulled or actuated in one direction by the piston rod against fluid in the water iner 3 a pressure will be acted upon element 7 and when this fluid pressure is suflicient it will cause the element or piston follower 7 to rotate and move in a longitudinal direction toward piston member 9 compressing the pliable packing 5 located therebetween. On the return stroke of the piston rod 1, in the opposite direction, the reaction of the piston packing 5 will not be sufiicient to rotate the piston follower 7. This feature permits follower 7 to hold the packing 5 in its compressed state, it being noted that the piston member 9 is fixed upon the piston rod 1 against longitudinal movement by the tapered part thereof 10 and the locknuts 11 which have threaded engagement 12 with the piston rod 1. Also it may be well to note that piston member 9 bears directly against the piston adapter 2 which is also fixed against longitudinal movement.

To merely reverse the location of piston follower 7 to the other side of the piston unit 4 or to have two piston followers or, in other words, two movable members similar to element 7 will obviously appear to those skilled in the art, I merely mention this to show it is in my knowledge to be able to do so without departure from the spirit of my invention.

My construction resides mainly in but four vto limit the end-wise travel of element 7,

and a series of square threads 8 which will have an extra large lead for threaded engagement with the piston follower 7. It may be well to state here that the threads 8 may be of any form or shape. The outer disposed hub 14 of adapter 2 permits a bearing for the inner diameter 15 of the pliable packing 5 and a male joint connection 16 with the element 9. This adapter will be fixed a ainst movement on piston-rod 1 by a wedge riven fit thereto. However a-setscrew may be incorporated in adapter 2 for'additional precaution against movement on piston rod 1 if so desired. It is obvious that the adapter 2 could be placed on the piston rod 1 with the raised shoulder 13 adjacent the locknuts 11 and one of the said locknuts 11 used to hold the adapter 2 from rotating or in other words to hold the adapter stationary, by forming the raised shoulder 13 to fit the said locknut 11.

Piston follower 7 is a cylindrical disc having threads 8 on its inner diameter for threaded engagement 8 with adapter 2. Its outer diameter being substantially the same as the diameter of the piston packing 5. Its end surface 17, adjacent the pliable, packing 5, being adapted to suit the end surface of the packing 5, which by the way may be of any desired shape or form. This piston follower 7 will rotate when moved in a longitudinal direction, which is obvious, due to its threaded engagement with the stationary adapter 2.

Piston member 9 is a cylindrical disc'in formation having an inner bore 18 to suit the diameter of the piston rod 1 and its outer diameter 19 will be about the same as the diameter of the piston packing 5. On one end portion a female joint indentation 20 is provided to make up a male and female joint connection with the adapter 2. This joint connection permits a centralizing means for this member 9 with the rest of the piston unit 4 and also this end portion will have a surface 17 similar to that of the adjacent end surface of the packing 5. This piston member 9 is fixed against longitudinal movement on the piston rod 1 by adapter 2 and locknuts 11. If desired this member 9 can have threaded engagement with the piston rod 1, and be used equally as well. It will be apparent to those skilled in the art, that piston member 9 and adapter 2 can be made in one piece without departure from the scope of my improvement.

Piston packing 5 is a hollow cylinder made of a pliable material preferably-of a rubber composition. In this case I have made it with a conical surface 17 on its end portions. However these said end surfaces can be made of any shape or form and used to equally good advantage. Its inner diameter will be mounted upon the adapter 2 and its outer diameter 21 will bear sufliciently against the walls of the water liner 3 of the pump in which it reciprocates. This packing 5 will be compressed and/or expanded b the movement of element 7 against its on surface 17 and/or by the fluid pressure in the pump. From the above description it will be noted that I have rovided a simple and effected means for ad usting the said packing 5 with a rotating movement of a single element acted upon by fluid pressure in the pump. To assemble this piston in the pump and to dismantle it from the pump will be apparent by referring to Figure 1 of the appended drawing without further description. To permit element 7 to rotate efliciently when using the pressure of the fluid in the pump as a motive power, I make the angle or lead of the threads 8 of a greater angle than the friction angle, or in other words the threads 8 have a greater thread angle than the tangent of the coeflicient of friction of the metals the said threads are made of.

In my copending application Serial No. 347,904, filed Mar. 18, 1929, it will be noted that the follower element therein does not rotate when being moved in a longitudinal direction and the construction referred to comprises a number of more parts than that of this improvement. It suflices to say that this construction is entirely different from that of my copending application and the results accomplished of a different nature.

What I claim and desire to secure by Le ters Patent is: I

1. In a reciprocating pump adapted to create a pressure on a fluid, a piston rod, a pump piston comprising a stationary element secured to the piston rod and an element adapted to revolve when acted upon by fluid pressure and having a continuous large lead thread winding around in it spirally at a con.- stant inclination so as to leave a like continuous groove between each turn and the next used for producing when revolved, pressure in the direction of its length by the sliding of the threads of the revolving element between 'the threads of the grooved perforations in the stationary element adapted to it, a head disposed element mounted on the piston rod, a

pliable packing disposed between the head disposed element and the revolving element whereby rotation of said revolving element by fluid pressure will change the relative positions of the head disposed elementand the revolving element and move the packing.

2. In a mechanism adapted to create a pressure on a fluid, a piston rod, a piston comprising an element adapted to be secured to the piston rod, a revoluble element having threaded engagement with the first named element and being so formed so as to be retated by fluid pressure, a pliable packing conneeted with the first named element and the revoluble element.

3. In a'mechanism adapted to create a pres sure on a fluid, a pump plunger comprising a plunger rod, a rotatory element being so formed so as to be rotated by pressure of fluid, a stationary element secured to the plunger rod and having threaded engagement with the rotatory element, the said threaded engagement comprising of threads having a greater thread angle than the angle of friction relative to the tangent of the coeflicient of frictionof the metals of the said rotatory element and stationary element, a pliable packing connected with the stationary element and the rotatory element.

4. In a reciprocating pump adapted to create a pressure on a fluid, a pump plunger comprising a plunger rod, a stationary element secured to the plunger rod, a revoluble element having an area adapted to be exposed to fluid and mounted on said stationary element with threaded engagement by threads having a greater thread angle than the angle of friction relative to'the tangent of the coefficient of friction of the metals of the said stationary element and revoluble element whereby, fluid under pressure acting against the said exposed area of the revoluble element will move said revoluble element and 

